Concept explainers
The physicist Stephen Hawking, famous for his theories about black holes, has lived past the age of 70 with amyotrophic lateral sclerosis (ALS), a paralyzing neurodegenerative disease that is usually fatal at a much younger age. Recently, geneticists discovered that a major cause of ALS is the unusual expansion of a hexanucleotide repeat (5′-GGGGCC-3′) that lies within a gene called C9ORF72, at a location outside of the gene’s open reading frame (ORF). A single expanded allele is sufficient to cause ALS, but the reason the disease allele is dominant remains unclear. Some experimental results support the theory that the allele makes a toxic RNA containing the expanded repeat. If this theory is correct, in what ways is the mutant ALS-causing allele similar to the mutant allele that causes Huntington disease? In what ways is it similar to the mutant allele that causes fragile X syndrome?
Want to see the full answer?
Check out a sample textbook solutionChapter 7 Solutions
Genetics: From Genes to Genomes
- Consider the now dominant variant of the SARS-CoV-2 called the D614G mutation: a) The mutation changes an Aspartate (D, Asp) to a Glycine (G, Gly) at nucleotide position 614 (that’s why it’s called the D614G mutant) in the S1 subunit of the Spike protein. Using only the information above and a codon table, what are the mRNA codon sequences of the 2019-dominant and 2020-dominant Spike proteins? Note the figure above is not needed toanswer the question. Report in 5’ to 3' orientation __________________________________________ b) What type of substitution is this? In your answer, address the following: • The expected substitution in base sequence (e.g., A à C)• If the mutation is synonymous, nonsynonymous, or a frameshift• If the mutation is a transition or a transversion c) The mutation increases infectivity by reducing the stability of the Spike protein such that it can remain in the open conformation more often. The open conformation increases the chances of binding to the host ACE2…arrow_forwardAs part of a project investigating potential new drug targets in the fight against malaria, you are seeking to clone the gene for a protein from the malaria parasite Plasmodium falciparum. You wish to express this protein in BL21 (DE3) cells, a standard laboratory strain of Escherichia coli. After purification of your protein, you run an SDS-PAGE gel and notice that the major band has lower molecular weight than expected, so you fear you are getting a truncated version. 1. What technique could you use to confirm that you are obtaining a shortened version of your intended protein? explainarrow_forwardAs part of a project investigating potential new drug targets in the fight against malaria, you are seeking to clone the gene for a protein from the malaria parasite Plasmodium falciparum. You wish to express this protein in BL21 (DE3) cells, a standard laboratory strain of Escherichia coli. After purification of your protein, you run an SDS-PAGE gel and notice that the major band has lower molecular weight than expected, so you fear you are getting a truncated version. (a) Give TWO possible causes of your protein becoming truncated. explainarrow_forward
- In the human genome for the beta chain of haemoglobin (the oxygen-carrying protein in the red blood cells), the first 30 nucleotide in the amino acid coding region is represented by the sequence 3'-TACCACGTGGACTGAGGACTCCTCTTCAGA-5'arrow_forwardThe mRNA sequence 5' AUG AAA CAG GGA UAA 3' encodes a particular peptide of interest to your research team. You have identified a new alternate allele of the sequence 5' AUG AAG CAG GGA UAA 3'. What type of mutation does this alternate sequence illustrate?arrow_forwardA molecular geneticist hopes to find a gene in human liver cells that codes for an important blood-clotting. He knows that the nucleotide sequence of a small part of the gene is GTGGACTGACA. Briefly explain how to obtain the desired gene.arrow_forward
- Duchenne muscular dystrophy is caused by a mutation in a gene that comprises 2.5 million base pairs and specifies a protein called dystrophin. However, less than 1% of the gene actually encodes the amino acids in the dystrophin protein. On the basis of what you now know about gene structure and RNA processing in eukaryotic cells, provide a possible explanation for the large size of the dystrophin gene.arrow_forwarda molecular geneticist hopes to find a gene in human liver cells that codes for an important blood-clotting protein. he knows that the nucleotide sequence of a small part of the gene is gtggactgaca. briefly explain how to obtain the desired gene answerarrow_forwardA molecular researcher, Dr. Sidra Alkatini, is investigating the manifestation of a disorder in some of her lab mice models, which are lacking production of an important protein necessary for the cellular respiration pathway. The afflicted mice are short lived, and have perpetually low blood glucose levels, no matter how much food they are fed. Through sequencing, the following strand of DNA was produced: 5’ TTC CAA TTA CGC CGC TAT ACG CGC ACC ATG TTA TCA TGT TGG TGG TAG 3’ Given your expertise in genetics, she contacts you, her BFF, to help her understand the sequence and its relation to the genetic disorder she is seeing. 1) What motif in this DNA sequence would serve as the RBS? a Essentially none; this is a eukaryotic sequence, so the RBS will be made up of the methylated G-cap! b CAAT! c ACCATGG! d TATA! 2) Do you notice anything unusual about this transcript? a YES! It is very short! b YES! It is…arrow_forward
- A molecular researcher, Dr. Sidra Alkatini, is investigating the manifestation of a disorder in some of her lab mice models, which are lacking production of an important protein necessary for the cellular respiration pathway. The afflicted mice are short lived, and have perpetually low blood glucose levels, no matter how much food they are fed. Through sequencing, the following strand of DNA was produced: 5’ TTC CAA TTA CGC CGC TAT ACG CGC ACC ATG TTA TCA TGT TGG TGG TAG 3’ Given your expertise in genetics, she contacts you, her BFF, to help her understand the sequence and its relation to the genetic disorder she is seeing. 1) Considering the entire DNA sequence shown above, specify the numbered codon that represents START. a Codon 10. b Codons 12-13. c Codon 9. d Codons 28-30. 2) Indicate three motifs that justify this as being a eukaryotic sequence. a CAAT, TATA, ACCATGG. b GACA, TATAAT, AAUAA.…arrow_forwardA molecular researcher, Dr. Sidra Alkatini, is investigating the manifestation of a disorder in some of her lab mice models, which are lacking production of an important protein necessary for the cellular respiration pathway. The afflicted mice are short lived, and have perpetually low blood glucose levels, no matter how much food they are fed. Through sequencing, the following strand of DNA was produced: 5’ TTC CAA TTA CGC CGC TAT ACG CGC ACC ATG TTA TCA TGT TGG TGG TAG 3’ Given your expertise in genetics, she contacts you, her BFF, to help her understand the sequence and its relation to the genetic disorder she is seeing. 1) Now that you have seen the sequence and identified some of the major motifs it contains, what are going to tell Dr. Alkatini about in relation to the genetic disorder she is seeing? a “Listen, Doc, it is clear there is no STOP signal in the last codon place where it normally should be.” b “Listen, Doc, the fact…arrow_forwardCystic fibrosis (CF) is an inherited disorder caused by different types of mutations, many of which prevent ions from moving across cell membranes. Normally there are channel proteins that allow passage of the ions, but in patients with one kind of CF these proteins seem odd. Closer examination shows that these proteins display the correct amino acid sequence. However, they fail to do their job. A) Given that the primary structure of the protein is correct, what can you infer about the DNA sequence for the gene coding this protein on this patient, is there a mutation? Explain. B) Why is the primary structure insufficient to guarantee the proper function of the protein?arrow_forward
- Human Anatomy & Physiology (11th Edition)BiologyISBN:9780134580999Author:Elaine N. Marieb, Katja N. HoehnPublisher:PEARSONBiology 2eBiologyISBN:9781947172517Author:Matthew Douglas, Jung Choi, Mary Ann ClarkPublisher:OpenStaxAnatomy & PhysiologyBiologyISBN:9781259398629Author:McKinley, Michael P., O'loughlin, Valerie Dean, Bidle, Theresa StouterPublisher:Mcgraw Hill Education,
- Molecular Biology of the Cell (Sixth Edition)BiologyISBN:9780815344322Author:Bruce Alberts, Alexander D. Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter WalterPublisher:W. W. Norton & CompanyLaboratory Manual For Human Anatomy & PhysiologyBiologyISBN:9781260159363Author:Martin, Terry R., Prentice-craver, CynthiaPublisher:McGraw-Hill Publishing Co.Inquiry Into Life (16th Edition)BiologyISBN:9781260231700Author:Sylvia S. Mader, Michael WindelspechtPublisher:McGraw Hill Education